cairoArc                package:RGtk2                R Documentation

_c_a_i_r_o_A_r_c

_D_e_s_c_r_i_p_t_i_o_n:

     Adds a circular arc of the given 'radius' to the current path. 
     The arc is centered at ('xc', 'yc'), begins at 'angle1' and
     proceeds in the direction of increasing angles to end at 'angle2'.
     If 'angle2' is less than 'angle1' it will be progressively
     increased by 2*M_PI until it is greater than 'angle1'.

_U_s_a_g_e:

     cairoArc(cr, xc, yc, radius, angle1, angle2)

_A_r_g_u_m_e_n_t_s:

    'cr': ['Cairo']  a cairo context

    'xc': [numeric]  X position of the center of the arc

    'yc': [numeric]  Y position of the center of the arc

'radius': [numeric]  the radius of the arc

'angle1': [numeric]  the start angle, in radians

'angle2': [numeric]  the end angle, in radians

_D_e_t_a_i_l_s:

     If there is a current point, an initial line segment will be added
     to the path to connect the current point to the beginning of the
     arc. If this initial line is undesired, it can be avoided by
     calling 'cairoNewSubPath' before calling 'cairoArc'.

     Angles are measured in radians. An angle of 0.0 is in the
     direction of the positive X axis (in user space). An angle of
     'M_PI'/2.0 radians (90 degrees) is in the direction of the
     positive Y axis (in user space). Angles increase in the direction
     from the positive X axis toward the positive Y axis. So with the
     default transformation matrix, angles increase in a clockwise
     direction.

     (To convert from degrees to radians, use 'degrees * (M_PI /
     180.)'.)

     This function gives the arc in the direction of increasing angles;
     see 'cairoArcNegative' to get the arc in the direction of
     decreasing angles.

     The arc is circular in user space. To achieve an elliptical arc,
     you can scale the current transformation matrix by different
     amounts in the X and Y directions. For example, to draw an ellipse
     in the box given by 'x', 'y', 'width', 'height':


     cr$save()
     cr$translate(x + width / 2, y + height / 2)
     cr$scale(1 / (height / 2), 1 / (width / 2))
     cr$arc(0, 0, 1, 0, 2 * pi)
     cr$restore()


_A_u_t_h_o_r(_s):

     Derived by RGtkGen from GTK+ documentation

